NASA uncovers new clues about the make-up of Pluto’s largest moon

Scientists have identified carbon dioxide and hydrogen peroxide on the surface of Pluto’s largest moon for the first time.

Data captured by NASA’s James Webb Space Telescope near-infrared spectrograph show new chemical clues on Charon.

Previously, in 2015, water ice, ammonia, and organic materials were detected on Charon during New Horizons, a NASA mission to study the dwarf planet, its moons, and other objects in the Kuiper Belt.

“New Horizons went by the Pluto system and gave us great resolved images of Charon and Pluto in the whole system,” Carly Howett, an associate professor at the University of Oxford, said.

“But of course, its wavelength range was limited to the instrument it flew, which cut off, I think, at 2.5 microns,” Howett added.

James Webb’s extended coverage

Webb’s extended wavelength coverage beyond previous limits helped detect chemicals lurking at certain infrared wavelengths.

“This extended coverage and enabled detection for the first time of carbon dioxide and hydrogen peroxide on the surface of Charon,” Silvia Protopapa, Study co-author at Southwest Research Institute, said.

The near-infrared spectrograph on the James Webb Space Telescope has about 5.2 microns while having lower spatial resolution.

Researchers used it to ensure full coverage of Charon’s northern hemisphere during four observations in 2022 and 2023.

“In that region, there’s a lot of stuff going on. There’s a lot of fingerprints of chemicals that we otherwise wouldn’t get to see,” Howett said.

“Things that we suspected were there but couldn’t say for certain were there. So it’s been a nice extra piece of the jigsaw puzzle in understanding what’s going on in the Pluto system,” Howett added.

New insights into Charon’s composition

The authors of the study say the discovery of carbon dioxide, which is ubiquitous in the solar system, was expected. What’s interesting is where it is found and how it’s structured to better understand the moon, they said.

Scientists believe the carbon dioxide might spew to the surface after impacts from space rocks and the hydrogen peroxide may have sprung from radiation pinging off water molecules on Charon’s surface.

“Hydrogen peroxide is something you only get from radiolysis of water… by detecting the levels we can see we have a constraint on how much radiation has been hitting Charo – perhaps which radiation is important in Chevron’s processing. So it sort of points to how it’s evolved,” said Howett.

Pluto and its moons are in the far fringes of our solar system in a zone known as the Kuiper Belt, over 4.8 billion km from the Sun.

ADVERTISEMENT

Scientists believe they are likely too chilly to support life. However, the latest detection is key to studying how Charon came to be and may help scientists tease out the make-up of other faraway moons and planets.

Video editor • Roselyne Min